CN114086114B

CN114086114B - Metal mask and method for manufacturing the same

Info

Publication number: CN114086114B
Application number: CN202111323122.0A
Authority: CN
Inventors: 陈韵珩; 林文宜
Original assignee: Darwin Precisions Corp
Current assignee: Darwin Precisions Corp
Priority date: 2021-06-11
Filing date: 2021-11-04
Publication date: 2023-05-05
Anticipated expiration: 2041-11-04
Also published as: TW202248740A; CN114086114A; US20220396866A1; TWI777614B; US11685985B2; US20230037092A1

Abstract

A metal mask includes a rolled metal material to form a metal mask substrate, wherein the metal mask substrate includes a surface and a plurality of trenches formed on the surface, the trenches extending in a direction. The surface has at least one sampling area, and a plurality of grooves are distributed in the sampling area, wherein the average area ratio between the areas of the grooves in the sampling area and the area of the sampling area is between 45% and 68%.

Description

Metal mask and method for manufacturing the same

Technical Field

The present invention relates to a tool for patterning process and a method for manufacturing the tool, and more particularly, to a metal mask and a method for inspecting the metal mask.

Background

Some display panels are manufactured by vapor deposition (evapration) and use a metal mask, wherein the metal mask has a plurality of openings. During evaporation, a plating material can be deposited through these openings onto a substrate (e.g., a glass plate) to be plated to form a patterned film. Conventional metal masks are typically fabricated using a photolithographic (photolithography) process, so that the openings are typically defined by a developed photoresist pattern.

The current trend of display panels has been toward high resolution, so the pitch (pitch) between the openings of the metal mask has to be reduced so that the metal mask can be used to manufacture the high resolution display panel. However. Once the space between the openings is reduced, the portion of the photoresist pattern covering the area between the two adjacent openings is also reduced, so that the photoresist pattern may not actually cover the area between the two adjacent openings during etching, which may result in the subsequent formation of some out-of-specification large-size openings, or even the formation of a plurality of openings connected to each other, which may make the manufactured metal mask unsuitable or unusable for manufacturing high-resolution display panels.

Disclosure of Invention

At least one embodiment of the present invention provides a metal mask that can be used for manufacturing a display panel.

Another embodiment of the present invention provides a method for manufacturing a metal mask, so as to manufacture the metal mask.

In a method of manufacturing a metal mask according to at least one embodiment of the present invention, first, a metal material is rolled to form a metal mask substrate, wherein the metal mask substrate includes a surface and a plurality of trenches formed on the surface, and the trenches extend in one direction. The surface has at least one sampling area, and a plurality of grooves are distributed in the sampling area, wherein the average area ratio between the areas of the grooves in the sampling area and the area of the sampling area is between 45% and 68%.

In at least one embodiment of the present invention, the manufacturing method further includes performing a photolithography process on the metal mask substrate.

In at least one embodiment of the present invention, the surface has a plurality of sampling areas. In the same sampling region, an area ratio is defined according to the areas of the grooves located in the sampling region and the areas of the sampling region, and the average area ratio is equal to the average value of the area ratios of the sampling regions.

In at least one embodiment of the present invention, the metal mask substrate further includes a pair of long sides opposite to each other and a pair of short sides opposite to each other, and the long sides connect the short sides. The sampling areas are distributed along the long sides, and the direction is parallel to the extending direction of the long sides.

The metal mask according to at least one embodiment of the present invention includes a surface, a plurality of trenches, and a plurality of openings. The surface has at least one sampling area. The grooves and the openings are formed on the surface, and the grooves extend towards the same direction, wherein the average area ratio between the areas of the grooves in the sampling area and the areas of the sampling area is between 45% and 68%.

In at least one embodiment of the present invention, the width of each trench is between 7 microns and 23 microns.

In at least one embodiment of the present invention, the metal mask further includes a pair of long sides opposite to each other and a pair of short sides opposite to each other, wherein the long sides connect the short sides, and the extending direction of the trench is parallel to the extending direction of the long sides.

In at least one embodiment of the present invention, the surface has a plurality of sampling areas, and the sampling areas are distributed along the long sides.

In another embodiment of the present invention, a metal mask is manufactured by first calendaring a metal material to form a metal mask substrate, wherein the metal mask substrate includes a surface and a plurality of trenches formed on the surface, and the trenches extend in the same direction. Then, at least one sampling area is selected on the surface. An average area ratio between the areas of the trenches in the sampling area and the area of the sampling area is measured and obtained. When the average area ratio is between 45% and 68%, the metal mask substrate is subjected to a photolithography process.

In at least one embodiment of the present invention, a plurality of sampling areas are selected on the surface, and the step of measuring and obtaining the average area ratio includes measuring and obtaining the area ratio defined by the areas of the trenches located in the sampling areas and the areas of the sampling areas in the same sampling area. Thereafter, the average value of the area ratios of these sampling areas was calculated.

When the average area ratio is between 45% and 68%, the surface of the metal mask substrate may have a suitable roughness that facilitates forming a metal mask with acceptable openings to enable the metal mask to be used in manufacturing a display panel.

The invention will now be described in more detail with reference to the drawings and specific examples, which are not intended to limit the invention thereto.

Drawings

FIG. 1A is a schematic diagram of a calendaring process used in a method of fabricating a metal mask according to at least one embodiment of the invention.

Fig. 1B is an enlarged schematic view of a portion of the surface of the calender roll of fig. 1A.

FIG. 2A is a schematic top view of a metal mask substrate formed by the calendaring process of FIG. 1A.

FIG. 2B is a schematic top view of the metal mask blank of FIG. 2A in one of the sampling areas.

Fig. 3A and 3B are schematic cross-sectional views of the metal mask substrate of fig. 2A during a photolithography process.

Fig. 3C is a schematic top view of the metal mask of fig. 3B.

Wherein, the reference numerals:

10: metal material

30: initial photoresist layer

31: photoresist pattern

31a, 31b: holes and holes

101: metal mask substrate

100: metal mask

110. 111: surface of the body

130: groove(s)

131. 211r: width of (L)

150: sampling area

151: side length

170: an opening

191: long edge

192: short side

200: calender

210: rolling roller

211: calendering layer

211p: bump

212: roller wheel

290: transmission roller

D1: first direction

D2: second direction

Detailed Description

In the following text, the dimensions (e.g., length, width, thickness, and depth) of elements (e.g., layers, films, substrates, regions, etc.) in the drawings are exaggerated in unequal scale for clarity. Accordingly, the following description and illustrations of the embodiments are not limited to the dimensions and shapes assumed by the elements of the drawings, but are intended to cover deviations in the dimensions, shapes, and both, that result, for example, from actual manufacturing and/or tolerances. For example, the planar surface shown in the drawings may have rough and/or nonlinear features, while the acute angles shown in the drawings may be rounded. Therefore, the elements presented in the drawings are mainly for illustration, and are not intended to precisely describe the actual shapes of the elements, nor to limit the scope of the claims.

Moreover, the words "about," "approximately" or "substantially" as used herein are intended to encompass not only the well-described values and ranges of values, but also the allowable deviation as understood by one of ordinary skill in the art, wherein the deviation is determined by the error in measurement, such as due to limitations in the measurement system or process conditions. Further, "about" may mean within one or more standard deviations of the above values, for example within ±30%, ±20%, ±10% or ±5%. The terms "about," "approximately" or "substantially" as used herein may be used to select an acceptable range of deviation or standard deviation based on optical, etching, mechanical or other properties, and not to cover all of the above with a single standard deviation.

FIG. 1A is a schematic diagram of a calendaring process used in a method of fabricating a metal mask according to at least one embodiment of the invention. Referring to fig. 1A, in the method for manufacturing a metal mask of the present embodiment, first, a metal material 10 is rolled to form a metal mask substrate 101. Specifically, the metallic material 10 may be fed into a calender (calendering machine) 200 for calendering, wherein the calender 200 includes a plurality of calender rolls (calendering roller) 210 and a plurality of transfer rolls 290.

The metal material 10 may be a flexible metal strip or a rigid metal sheet, wherein some of the transfer rollers 290 are capable of feeding the metal material 10 between the calender rollers 210 such that two adjacent rotating calender rollers 210 are capable of calendering the metal material 10 to form the metal mask substrate 101. Other transfer rollers 290 are capable of transferring the calendered metal mask substrate 101 such that the metal mask substrate 101 exits the calendering rollers 210 and is output from the calender 200.

It should be noted that the calender 200 shown in fig. 1A may include four calender rolls 210, wherein the four calender rolls 210 may simultaneously calender the same metal material 10. In addition, in the present embodiment, at least two of the calender rolls 210 may be different in size. Taking fig. 1A as an example, the size of the left two calender rolls 210 is significantly larger than the size of the right two calender rolls 210. However, in other embodiments, the dimensions of the calender rolls 210 may be substantially the same as each other, so fig. 1A does not limit the dimensions of the calender rolls 210.

Fig. 1B is an enlarged schematic view of a portion of the surface of the calender roll of fig. 1A. Referring to fig. 1A and 1B, each calender roll 210 may include a calender layer 211 and a roll 212. In the same rolling roller 210, the rolling layer 211 covers the outer surface of the roller 212, so that the rolling layer 211 surrounds the roller 212, wherein the rolling layer 211 may be fixed on the roller 212 by using an adhesive manner, and the material of the rolling layer 211 may be titanium.

The surface of the rolled layer 211 may have a plurality of bumps 211p capable of pressing the metal material 10 to form a plurality of grooves on the surface of the metal material 10. The bumps 211p have a variety of different dimensions, and the width 211r of the bumps 211p may be substantially between 7 microns and 23 microns. Further, in the present embodiment, the bumps 211p may be irregularly arranged as shown in fig. 1B. However, in other embodiments, the bumps 211p may be arranged in a regular manner, such as a matrix arrangement.

Note that the bumps 211p are densely distributed in practice. However, fig. 1B is an enlarged schematic view of a portion of the surface of the calender roll 210, and fig. 1B schematically illustrates the surface of the calender roll 210, for example, by reducing the number of calender rolls 210, so that fig. 1B can simply and clearly present the bumps 211p, thereby facilitating the marking of the bumps 211p and the width 211r. Accordingly, fig. 1B is merely illustrative and is not intended to precisely depict the actual appearance of the surface of the calender roll 210.

FIG. 2A is a schematic top view of a metal mask substrate formed by the calendaring process of FIG. 1A. Referring to fig. 2A, the metal mask substrate 101 includes a surface 110 and a plurality of grooves 130 formed on the surface 110, wherein the grooves 130 are formed by pressing the metal material 10 by the calender rolls 210. Thus, the trenches 130 all extend in the same direction. For example, in fig. 2A, the trenches 130 may be parallel to each other and extend along the first direction D1.

The metal mask base 101 further comprises a pair of long sides 191 opposite to each other and a pair of short sides 192 opposite to each other, wherein the long sides 191 connect the short sides 192. In the present embodiment, the extending direction of the long sides 191 may be substantially parallel to the first direction D1, and the extending direction of the short sides 192 may be substantially parallel to the second direction D2, wherein the first direction D1 may be substantially perpendicular to the second direction D2.

It should be noted that, from the embodiment shown in fig. 2A, the length of each groove 130 is substantially equal to the length of the long side 191. However, in other embodiments, the length of the at least one groove 130 may be less than the length of the long side 191. For example, during the above-described calendaring process, the plurality of bumps 211p can extrude at least two non-connected, but co-linear grooves 130. Thus, the length of one groove 130 shown in FIG. 2A may be less than the length of the long side 191, and need not be equal to the length of the long side 191.

In addition, since the bumps 211p of the same calender roll 210 are densely distributed in practice, the parallel grooves 130 are densely distributed. However, fig. 2A schematically illustrates the trenches 130, for example, by reducing the number of the trenches 130, so as to simply and clearly present the trenches 130. Accordingly, fig. 2A is merely illustrative and is not intended to precisely depict the actual appearance and true distribution of the grooves 130.

Then, at least one sampling area 150 is selected on the surface 110 of the metal mask substrate 101, such that the surface 110 has at least one sampling area 150. The sampling area 150 may be marked on the surface 110, i.e. the sampling area 150 is visible. Alternatively, the sampling area 150 may be left untagged on the surface 110, i.e., the sampling area 150 is not visible.

For example, the sampling region 150 may be selected by an instrument, wherein the instrument may be an optical measurement instrument, such as an optical microscope or an optical dimension measurement instrument. The optical metrology tool may select at least one sampling area 150 directly on the surface 110 of the metal mask substrate 101 without using a mark, so that the sampling area 150 may be invisible to the human eye.

In the embodiment shown in fig. 2A, a plurality of sampling regions 150 are selected on the surface 110 of the metal mask substrate 101, such that the surface 110 has a plurality of sampling regions 150, wherein the sampling regions 150 may be distributed along the long sides 191, i.e., the sampling regions 150 may be distributed along the first direction D1. However, in other embodiments, only one sampling region 150 may be selected on the surface 110, i.e., the surface 110 has only a single sampling region 150. Thus, the surface 110 may have only one sampling area 150, not limited by FIG. 2A.

FIG. 2B is a schematic top view of the metal mask blank of FIG. 2A in one of the sampling areas. Referring to fig. 2A and 2B, a plurality of trenches 130 may be distributed in each sampling region 150, so that at least two trenches 130 that are parallel to each other and not collinear (noncollinear) are formed in a single sampling region 150, as shown in fig. 2B.

In the present embodiment, the shape of the sampling area 150 may be substantially square, wherein the side length 151 of the sampling area 150 may be, for example, about 5 mm. In other words, the shape of the sampling region 150 may be substantially a square of 5 mm×5 mm. The trenches 130 may be formed by pressing the metal material 10 by the bumps 211p, so that the width 131 of each trench 130 is substantially equal to the width 211r of the bump 211p (see fig. 1B). Thus, the width 131 of each trench 130 may be between 7 microns and 23 microns.

It should be noted that the width 131 of each trench 130 may be between 7 μm and 23 μm, and the side length 151 of the sampling region 150 may be about 5 mm, so it is apparent that fig. 2A and 2B do not draw the sampling region 150 and the trench 130 in equal proportion according to the actual dimensions. Second, the trench 130 shown in fig. 2B is also not drawn to scale up fig. 2A. Accordingly, fig. 2A and 2B are not intended to accurately depict the trench 130 and the sampling region 150, but the trench 130 and the sampling region 150 shown in fig. 2A and 2B are merely illustrative to help illustrate the trench 130 and the sampling region 150

Further, since the bumps 211p of the calender roll 210 are densely distributed in practice, the same groove 130 may be formed by calendering the metal material 10 with a plurality of bumps 211 p. Thus, the shape of the single groove 130 is not necessarily rectangular, although it is a stripe. For example, the grooves 130 may be formed by connecting a plurality of circular holes and/or oval holes aligned in a line, such that the grooves 130 may have edges similar to waves and have a significantly uneven width. Accordingly, the trenches 130 shown in fig. 2B are for illustration only to help illustrate structural features of the present embodiment, and are not intended to precisely depict the trenches 130.

After one or more sampling regions 150 are selected, the average area ratio between the areas of the trenches 130 in each sampling region 150 and the area of the sampling region 150 is measured and obtained. In the process of measuring and obtaining the average area ratio, the areas of the trenches 130 in the sampling area 150 and the area of the sampling area 150 in the same sampling area 150 can be measured and obtained first, wherein the areas of the trenches 130 are equal to the sum of the areas of the trenches 130 in the same sampling area 150.

Taking fig. 2B as an example, the area of the sampling region 150 shown in fig. 2B (i.e., the side length 151×the side length 151) and the area of all the trenches 130 in the sampling region 150 can be measured. Then, the area ratio defined between the areas of all trenches 130 in the sampling area 150 and the area of the sampling area 150 is calculated. For example, in FIG. 2B, the area of the sampling region 150 is A, and the area of all trenches 130 in the sampling region 150 is T, wherein the above-mentioned area ratio is equal to T/A.

The average area ratio can be obtained from the area ratio defined by the areas of the trenches 130 in the sampling region 150 and the area of the sampling region 150. In detail, the area ratio of the sampling areas 150 is measured and obtained according to the definition of the area ratio. Thereafter, an average of the area ratios of the sampling areas 150 is calculated, wherein the average is equal to the average area ratio and may be an arithmetic average.

Then, it is determined whether the average area ratio falls within a qualified range, for example, between 45% and 68%, to determine whether the metal mask substrate 101 can be subjected to a subsequent process. When the average area ratio falls within a acceptable range, such as between 45% and 68%, the surface 110 of the metal mask substrate 101 has a roughness suitable for subsequent processing, such as photolithography.

Fig. 3A and 3B are schematic cross-sectional views of the metal mask substrate of fig. 2A during a photolithography process. Referring to fig. 3A, an initial photoresist layer 30 may be formed on a surface 110 of a metal mask substrate 101 during a photolithography process. Since the surface 110 has a proper roughness, the initial photoresist layer 30 covering the surface 110 can be closely adhered to the surface 110.

Referring to fig. 1A and 3A, it is particularly mentioned that in the present embodiment, the metal material 10 may be rolled by two rolling rollers 210 adjacent to each other and rotating, wherein each rolling roller 210 has a plurality of protruding points 211p, and thus, two opposite surfaces (including the surface 110) of the metal mask substrate 101 have a plurality of grooves 130. Taking fig. 3A as an example, the metal mask substrate 101 further has a surface 111 opposite to the surface 110, wherein a plurality of trenches 130 are also formed on the surface 111.

As with surface 110, surface 111 also has at least one sampling area, wherein the sampling area of surface 111 and sampling area 150 may have the same size and shape. Next, the method of measuring and obtaining the average area ratio from the surface 111 is also the same as the method of measuring and obtaining the average area ratio from the surface 110, so that the description will not be repeated.

After the average area ratio is obtained from the surface 111, it is also determined whether the average area ratio falls within a pass range, wherein the pass range may also be between 45% and 68%. When the average area ratio of the

surfaces

110 and 111 is between 45% and 68%, for example, it means that the

surfaces

110 and 111 have appropriate roughness, so that the two initial photoresist layers 30 can be tightly covered and adhered on the

surfaces

110 and 111, respectively.

Referring to fig. 3B, the initial photoresist layers 30 are developed to form two photoresist patterns 31, wherein the photoresist patterns 31 have a plurality of holes 31a and 31B (fig. 3B shows only one hole 31a and one hole 31B). In the embodiment shown in fig. 3B, the upper photoresist pattern 31 has a plurality of holes 31a exposing the surface 110, and the lower photoresist pattern 31 has a plurality of holes 31B exposing the surface 111, wherein the size of the holes 31a is significantly smaller than the size of the holes 31B.

After forming the photoresist patterns 31, the metal mask substrate 101 is etched using the photoresist patterns 31 as a mask such that a plurality of openings 170 (one opening 170 is shown in fig. 3B) are formed on the

surfaces

110 and 111 of the metal mask substrate 101, thereby forming the metal mask 100, wherein each opening 170 extends from the surface 110 to the surface 111. That is, the opening 170 is formed through the metal mask substrate 101.

Since the

surfaces

110 and 111 have appropriate roughness, not only the initial photoresist layers 30 can be tightly covered and adhered to the

surfaces

110 and 111, respectively, but also the photoresist patterns 31 can be tightly covered and adhered to the

surfaces

110 and 111, respectively. Therefore, during the etching process of the metal mask substrate 101, the photoresist patterns 31 can effectively prevent the etching solution from entering the areas except the

holes

31a and 31b of the photoresist patterns 31, so that the shape and the size of the two ends of the opening 170 can be substantially the same as the shape and the size of the

holes

31a and 31b, respectively.

Fig. 3C is a schematic top view of the metal mask of fig. 3B. Referring to fig. 3B and 3C, the photoresist patterns 31 are removed to expose both

surfaces

110 and 111. To this end, a metal mask 100 comprising

surfaces

110 and 111, a pair of long sides 191, a pair of short sides 192, a plurality of trenches 130, and a plurality of openings 170 is substantially fabricated.

Since the

surfaces

110 and 111 are covered by the photoresist patterns 31 during etching of the metal mask substrate 101, the trenches 130 included in both the metal mask 100 and the metal mask substrate 101 have substantially the same width (e.g., the width 131 shown in fig. 2B), and the average area ratio measured from the

surfaces

110 and 111 of the metal mask 100 falls within a qualified range, e.g., between 45% and 68%.

It should be noted that in the embodiment shown in fig. 3A and 3B, the initial photoresist layers 30 are developed to form the photoresist patterns 31. However, one of the calender rolls 210 in fig. 1A may not have any bump 211p, so that only one side of the metal material 10 is pressed by the bump 211p and the other side is not pressed by the bump 211 p. Thus, the trenches 130 are formed only on one side of the metal mask substrate 101, e.g., only on the surface 110, and not on the surface 111.

When the trench 130 is formed only on the surface 110, the initial photoresist layer 30 covering the surface 111 may not be developed so that the initial photoresist layer 30 can always cover the surface 111 during etching of the metal mask substrate 101, thereby preventing the etching solution from contacting the surface 111. Thus, the hole 31B shown in FIG. 3B may be omitted and the opening 170 may be etched from only one side (e.g., the surface 110) of the metal mask substrate 101.

In summary, when the average area ratio obtained according to the sampling region falls within a qualified range (e.g., between 45% and 68%), the surface of the metal mask substrate has a proper roughness, so that the photoresist pattern can be tightly covered and adhered on the surface of the metal mask substrate during the photolithography process. Thus, the openings of the metal mask can be formed substantially entirely in accordance with the holes of the photoresist pattern to reduce or avoid the off-specification openings, thereby making the metal mask suitable for manufacturing display panels, particularly for manufacturing high resolution display panels.

Although the present invention has been described with reference to the above embodiments, it should be understood that the invention is not limited thereto, but rather may be modified or altered without departing from the spirit and scope of the invention.

Of course, the present invention is capable of other various embodiments and its several details are capable of modification and variation in light of the present invention by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method of manufacturing a metal mask, comprising:

a metal material is rolled to form a metal mask substrate, wherein the metal mask substrate comprises a surface and a plurality of grooves formed on the surface, the grooves extend towards a direction, the surface is provided with at least one sampling area, the grooves are distributed in the at least one sampling area, and an average area ratio between the area of the grooves in the at least one sampling area and the area of the at least one sampling area is between 45% and 68%.

2. The method of manufacturing a metal mask according to claim 1, further comprising:

a photolithography process is performed on the metal mask substrate.

3. The method of claim 1, wherein the surface has a plurality of sampling regions, an area ratio is defined in the same sampling region according to an area of the trench located in the sampling region and an area of the sampling region, and the average area ratio is equal to an average value of the area ratios of the sampling regions.

4. A method of manufacturing a metal mask according to claim 3, wherein the metal mask substrate further comprises a pair of long sides opposite to each other and a pair of short sides opposite to each other, the long sides being connected to the short sides, the sampling areas being distributed along the long sides, the direction being parallel to the direction of extension of the long sides.

5. A metal mask, comprising:

a surface having at least one sampling region;

a plurality of trenches formed on the surface, each trench extending in a direction, wherein an average area ratio between an area of the trench in the at least one sampling region and an area of the at least one sampling region is between 45% and 68%; and

a plurality of openings formed in the surface.

6. The metal mask of claim 5, wherein each trench has a width of between 7 microns and 23 microns.

7. The metal mask according to claim 5, further comprising a pair of long sides opposite to each other and a pair of short sides opposite to each other, and the long sides connect the short sides, the direction being parallel to the extending direction of the long sides.

8. The metal mask of claim 6, wherein the surface has a plurality of the sampling regions, and the sampling regions are distributed along the long side.

9. A method of manufacturing a metal mask, comprising:

calendaring a metal material to form a metal mask substrate, wherein the metal mask substrate comprises a surface and a plurality of grooves formed on the surface, and the grooves extend towards one direction;

selecting at least one sampling area on the surface;

measuring and obtaining an average area ratio between the area of the groove in the at least one sampling area and the area of the at least one sampling area; and

when the average area ratio is between 45% and 68%, a photolithography process is performed on the metal mask substrate.

10. The method of claim 9, wherein the step of measuring and obtaining the average area ratio comprises selecting a plurality of sampling areas on the surface:

measuring and obtaining the area ratio of the area of the groove in the sampling area to the area defined by the area of the sampling area in the same sampling area; and

an average value of the area ratio of the sampling area is calculated.